Positron emission tomography (PET) is attracting attention as an effective inspection method for earlier diagnosis of cancer, cerebrovascular disease, dementia, etc. In PET, a compound labeled with a trace amount of positron emitting nuclides is administered and annihilation radiation emitted from inside the body is detected to image metabolic functions such as sugar metabolism and check for a disease and its extent. PET devices for practicing PET have been put into actual use.
To improve the sensitivity of a PET device, as illustrated in FIG. 1(a), a detector 10 needs to be arranged in a tunnel-like configuration for an increased solid angle. The long tunnel-shaped patient port, however, increases psychological stress on a patient 6 under examination as well as obstructs the patient's treatment. In view of this, the applicant has proposed an open PET device (also referred to as OpenPET) as illustrated in FIG. 1(b). In the open PET device a plurality of separate detector detectors 11 and 12 are arranged apart in the direction of the body axis to provide a physically open field of view area (also referred to as an open field of view) (WO 2008/129666 publication).
An open PET device enables PET diagnosis during treatment and whole-body simultaneous scanning, which have not been possible with conventional PET devices. Application to real-time PET/CT is also possible. Specifically, treatment can be applied to an open field of view between the detector rings. In an example of radiation cancer therapy, as shown in FIG. 2(a), it is possible to check the position of the cancer by using the open PET device during irradiation with a radiation treatment beam, or visualize the irradiation field of a radiation treatment beam with the open PET device in real time. Since an open PET device can extend the field of view in the direction of the body axis as much as the open field of view without increasing detectors, it is possible to build a PET device that can scan the whole body at a time (also referred to as a whole-body simultaneous field of view PET device) as shown in FIG. 2(b). In the diagram, 11 to 14 designate four detector rings, for example. PET devices capable of whole-body simultaneous scanning are expected to be useful even for the promotion of microdose tests which are attracting attention as a method for improving the development efficiency of drugs. The application of an open PET device to a PET/CT device which has become prevalent recently can easily provide the configuration that an X-ray CT device 20 is disposed in an open space interposed between two detector rings as shown in FIG. 2(c). It is therefore possible to build a real-time PET/CT device for simultaneous diagnosis of the same location, which has not been possible with conventional PET/CT devices. While the example has dealt with a CT device, any imaging devices may be installed in the open space.
As has been described above, an open PET device is expected to be the core of various use forms such as a whole-body simultaneous field of view PET device and a real-time PET/CT device. It may be difficult, however, to install various devices at a time since respective PET devices are expensive. Considering a wide variety of use forms of PET, including cancer screening, ordinary facilities such as a hospital do not always need an open PET device for all inspections from the early stage. Facility planning then needs to take account of up to final use forms, and devices need to be gradually added after initial installation of minimum necessary equipment. The devices need also be planned so that the added devices interact effectively to minimize the idle time of the respective devices.
It is therefore desired that device configurations can be changed depending on the type of inspection, whereas complicated changes in device configuration are unfavorable because PET devices and CT devices are heavy in weight and susceptible to vibrations etc.